Foundations_SP09_Exam2

Foundations_SP09_Exam2 - Name: Score: GEE 4433 —...

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Unformatted text preview: Name: Score: GEE 4433 — FOUNDATION ENGINEERING SPRING 2009 EXAMINATION || 11 MARCH 2009 General Instructions: (1) (2) (3) The test is open book and open notes. You may use any design resource you feel is necessary except those involving a computer or your classmates. Unless the problem specifically indicates to the contrary, assume that a FS=3 should be applied to the net ultimate bearing capacity to determine net allowable bearing capacities. Further assume the net ultimate bearing capacity can be adequately approximated by the form of the general bearing capacity equation that we have used in class. The appropriate factor of safety for all problems is the ratio of the net ultimate soil bearing capacity to the actual net applied bearing pressure. Pay careful attention to any NOTES that are specific to each problem (or part of a problem). (1) _ ~‘-_ , .‘4 t'. _ _- _ - - _ {V _ 3 * i r "9.3.391"? ‘93: 15 pts Department Of Education, Baton Rouge, Louisiana Remarkably, Louisiana DOES have a Department of Education, and it is to be housed in a multi-story building in Downtown Baton Rouge. The design engineer for the project is investigating the idea of creating a basement for the building to serve two purposes. First, the basement will provide off-street parking that is concealed for aesthetic reasons. Second, and more important for your work, the basement will serve as a “compensated foundation” by relieving net applied bearing pressures which would be developed from the superstructure loads. The design structural engineer has provided an estimate of the dead loads and live loads from the superstructure (i.e., all loads above the top of the concrete mat), and has divided these loads by the footprint of the structure, as shown below. Estimate the depth of the basement that will be required so that the immediate settlements of the building will be essentially zero. For the purposes of this calculation, you may assume that the water table is located at an infinite depth. You may also assume that the building footprint is “very large” (e.g., at least 150 feet by 150 feet in plan dimensions). SUPERSTRUCTURE IMPOSES AVERAGE PRESSURES OVER ITS FOOTPRINT: 1100 PSF DL (UNFACTORED) UNFACTORED 1350 PSF LL ( ) . I .. - 3&3 .. . .. 4 . . 4 , ii" 74 , . a , u A ,‘ .. . ...‘.‘:.:,:.$:V N é.‘:€‘.":"§‘.‘:é. . .. . ... ... .. .. ~ A. ' I§.%I'.E§fi§l§éié‘ifilfi” fi ..'p..‘p-.:\> , ~ I, . . 1'9 I y’ ‘ FOUNDATION soiL _ I ‘Y=128PCF” -:- ” (2) 20 pts Liggio Holdings, GulfggerMississ'in The owner of a bulk products terminal has decided to build a storage tank to hold 40,000 gallons of vegetable oil. The tank is to be a 20-ft diameter cylindrical steel tank, as shown below. The structural engineer proposes to support the tank by a concrete mat foundation, to aid in distributing the tank loads to the loose, sandy foundation soils. You have been instructed to assume the tank contents will be maintained at a level no higher than 90% of the tank height during operation. For convenience, the mat will be slightly oversized (relative to the tank) and will be poured in the shape of a square. A geotechnical boring was performed at the site, revealing the conditions shown below. Is the mat adequate to support the proposed tank? 20-FT NOMINAL DIAMETER 20-FT INTERNAL HEIGHT 0.300-INCH THICK 16 KIP 7“ CYLINDRICAL STEEL WIND SHEAR STORAGE TANK (DL, LF==1.4) 11 FEET ABOVE VEGETABLE OIL, Y = 58PCF GROUND SURFACE (LL, LF=1.7) 4 FEET 6 FEET -: 5-": '{z’si-‘I-zi:i:-'.=.:-:-':3.§:5L6QSEITQ‘MED'UM DENSE .. . -;:;TAN.'Elng-SAND (SP) " : {€5.22 PCF '22:} 5 {NC éE'zé‘A'T~?Q-'EZI1=§ST'2'2-'5': 3" ' (3) 65 pts 35 pts 30 pts Proposed Office Com_plex,_0ktibbeha Counmrliflississip‘pj A developer has proposed to locate a 90,000 ft2 office and research complex on a 10—acre site in Oktibbeha County. At present, the building is planned as a three—story, steel-framed structure occupying plan dimensions of 180 feet by 180 feet. Columns for the structure are to be positioned on a 30-ft grid spacing along both axes of the building. The structural engineer for the project has estimated preliminary sizes for the columns, girders, and joists along with a preliminary section for the first floor, upper floors, and roof. From these preliminary designs, the structural engineer has developed a typical framing plan and a first—floor interior column section and furnished these to you (see the following page). The structural engineer, being a structural engineer, would rather not concern himself with too many of the details of your analyses. For this reason, he has opted to provide you with loading data from the superstructure, as shown on the following pages. He has further estimated that the wind loading will cause a variation of approximately +/- 5 kips (unfactored) from the column loads he has estimated from vertical loads only. NOTE: The structural engineer has decided to include an “isolation joint” between the first floor slab and the footings at each column. The presence of this joint is intended to prevent load transfer between the first floor slab and the footing. Meanwhile, you are concurrently performing the geotechnical investigation of the site. From the field logs of the soil borings and the laboratory testing program, you have assembled a cross-section through the center of the building, as shown on the following pages. From the information provided: Estimate a s'ngle value of the net allowable bearing capacity that you will report to the structural engineer. This value must be justified by calculations, as the owner has indicated that all design work for the project will be subjected to an independent external technical review (and your primary competitor has been hired as part of the review team). Assume that footings within a proposed fill will not affect the reported value (as you will later specify properties for the fill and construction procedures which will ensure the fill material does not govern the foundation designs). NET ALLOWABLE BEARING CAPACITY (IN PSI:z ROUNDED TO NEAREST 100 PSF) Estimate the immediate settlement of the footing at Column D-4. IMMEDIATE SETTLEMENT AT 04 jIN INCHES, ROUNDED TO NEAREST 1/8 INCH) XMIEEOO MOWEO DmmOmomm m.__u_omn_ .__0w :0 \i <0; @zmmwmzmozm Eaim m3<> Em u z E E S u :02: 9.; E om u :02. r 08? E mzokmméfl .rth. waommnfimmmcm WW1“ EEG 5.53 0 EN I \\ w \/ \ \ \\ W \ 3.5 © 03:? :Nm \ 33 © omovamzwm \ . r . . H 0 0mm \ 0 0mm © OSBER \ o 8N @ 083:8 \ :8 >415 >55 mm. \ \ \ 226% ES W \ 0an © ommzfizom \ 3% © szmfiam \ "Efiw 0... E393 N m \ \ \ M 0.0% I \ 0.08 © om? :8 :8 0.0mm © 082328 \ v \ \ E a 3mm 0me © oonmzom WEN . . . 3 u z . b, V . .. - m... Odom 9? 1-1 opmmwfl 8 u z . > 11... 43% © w z m. I . _ _ H u g. .. IIIIumHEN“HHflflmflflflfiflflflflflflmHTHHHHHHHH ,IIIHIIIIWILHHWIIHIIHIIIIdedIWu©AwHWZ IRE.“le 0.8m .3 "29:3me x00: BIQZE mo; __ . m . mmz: firm/B m< 226% mum/E0 owonoE : 0 New © 8 u z .....H.......H 2 u n" 1 L a a é . F 2 E2: 330w @4 33015 "a mz: 223.60 2 w. m o Sm “fl 2 020.2 mofimam azaomw ozfimim 2 u. @ Q @ @ @ mg g,“ + ........ {an ........ I” ........ l; uuuuuuuuu -H ......... 1% ........ Ilu "A .562 u 05 =98 E 822% 9mm @ v. odwm iodNN odwN J 0.0mm (CI/\EDN) i333 NI NOILVAEI'IEI 30'—0" w12X96 W12X96 W24 x 55 30 I _ O " CLH' r16 STEELJOISTS AT 6—FT C/C W2 x 55 W12X96 W12X96 FRAMING PLAN — INTERIOR BAY TYPICAL UPPER FLOORS AND ROOF AVERAGE DL = 55 PSF FLOORS, 60 PSF ROOF (INCLUDES ALL STRUCTURAL MEMBERS) AVERAGE LL = 50 PSF FLOORS, 20 PSF ROOF (INCLUDES ALL ENVIRONMENTAL LOADS EXCEPT WIND) W12X96 COLS. 0.5-INCH ISOLATION JOINT AT 30-FT C/C AROUND PERIMETER OF FOOTING FINISHED FLOOR, EL. 302.0 EXISTING GRADE 6_INCH PCC SLAB Y (EL. VARIES, SEE SECTIONS) _ ’\ ~~~ ”'- 6-INCH COARSE SAND FILL OVER VAPOR BARRIER SQUARE FOOTING TYPICAL OF INTERIOR (SIZE VARIES, SEE SCHEDULE) ...
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Foundations_SP09_Exam2 - Name: Score: GEE 4433 —...

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